Question

A scientist is tracking the evolution of a gene in giant African snails that determines the direction of the spiral in shells. The following DNA sequence data was taken from a population of giant African snails:



DNA from Snail Parent for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

T

T

A

C

G

C

A

T

A

C



DNA from Snail Offspring #1 for Corkscrew Shell Gene:

A

A

T

T

C

G

T

A

T

G

T

T

A

A

G

C

A

T

A

C



DNA from Snail Offspring #2 for Corkscrew Shell Gene:

A

A

T

C

G

T

A

T

G

T

T

A

G

C

A

T

A

C



DNA from Snail Offspring #3 for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

G

T

T

A

C

G

C

A

T

A

C

C



DNA from Snail Offspring #4 for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

T

T

A

C

G

C

A

T

A

C



Compared to the parent’s DNA sequence, identify the snail offspring that has a substitution mutation in the corkscrew shell gene.

(1 point)
Responses

Offspring #4
Offspring #4

Offspring #3
Offspring #3

Offspring #2
Offspring #2

Offspring #1

Answer 1

To identify which snail offspring has a substitution mutation compared to the parent’s DNA sequence, we can compare each offspring’s DNA sequence with the parent's sequence.

**Parent's DNA Sequence:**
```
A A T G C G T A T G T T A C G C A T A C
```

**Offspring DNA Sequences:**
1. **Offspring #1:**
```
A A T T C G T A T G T T A A G C A T A C
```
- Mutation: Position 3 (G -> T), Position 12 (C -> A)

2. **Offspring #2:**
```
A A T C G T A T G T T A G C A T A C
```
- Mutation: Position 3 (G -> C), Position 12 (A -> G)

3. **Offspring #3:**
```
A A T G C G T A T G G T T A C G C A T A C C
```
- Mutation: Position 8 (T -> G), Position 12 (C -> T), Position 18 (C -> C) - Multiple substitutions

4. **Offspring #4:**
```
A A T G C G T A T G T T A C G C A T A C
```
- No mutations

Based on this comparison:
- **Offspring #1** has mutations at positions 3 and 12 (not a single substitution).
- **Offspring #2** has a substitution at position 3.
- **Offspring #3** has multiple mutations.
- **Offspring #4** has no mutations.

**Conclusion:**
Offspring #2 has the substitution mutation in the corkscrew shell gene.

**Response: Offspring #2**